* Split plural strings with multiple sentences to avoid duplicating translations.
* Decouple strings where the singular and plural form are not just the same string with different numbers, but essentially two different strings.
* Use an established pattern for numbered placeholders in translator comments.
* Replace constants in translatable strings with placeholders, mark them as code.
* Make sure sentences are translated as a whole, not as separate string parts.
* Remove unnecessary context and escaping.
Props ocean90, SergeyBiryukov.
See #46683.
git-svn-id: https://develop.svn.wordpress.org/trunk@45099 602fd350-edb4-49c9-b593-d223f7449a82